1. Field of the Invention
The invention relates to a separating-and lubricating agent in solid form for warm metal shaping, especially for warm-sheet or profile rolling and for example also a mandrel lubricant in the production of seamless pipes.
2. Prior Art
It is known to use glass lubricants, salt lubricants and laminary lubricants on a graphite basis, or aqueous emulsions with synthetic, surface active agents as separating and lubricating agents for non-cutting metal processing. Except for the laminary lubricants, based upon graphite, all of the other lubricants are not useable for hot sheet rolling. Glass or glass-like lubricants cannot be used since they can barely be detached from the surface of the process pieces. Salts, as lubricants in the form of aqueous solutions, lead to extensive corrosion on the workpiece and the machines. The use of lubricating and cooling fluids requires an additional apparatus for their cooling and cleaning in order that the fluid can be circulated.
In order to circumvent such disadvantages, which are known to the experts, a solid lubricant in the shape of briquets was described in Steel in the USSR, February 1974, pp. 153 and 154, and in Chemical Abstracts, Vol. 81, 1974, 109708k. The solid briquet-shaped lubricant, which is based upon graphite, also contains clays and surface-active additives. Such solid lubricant is pressed against the operating rollers of a rolling mill for producing steel by an apparatus, whereby a thin film of lubricant is applied to the operating rollers. The lubricant however still had disadvantages, as enumerated by Meleshko, Tubol'tsev and Adamskii, "Steel in the USSR", October 1979, pp. 515 to 519. According to page 516, lefthand column, it was impossible to obtain a finely-distributed even film of lubricant over the entire width and periphery of the roller by pressing the lubricant briquets thereon. That led to an uneven surface load of the rollers and sheets and to the destabilization of the rolling process.